Formaldehyde free binder compositions for fibrous materials

ABSTRACT

Compositions for binding organic or inorganic fibers is described. The compositions may include an aqueous solution having a pH of about 4.5 or more. The aqueous solution may include a polycarboxy polymer that is about 10%, by wt., to 100%, by wt., of a butenedioic acid or butenedioic anhydride; and a polyol. The compositions can maintain a pH of about 5 or more after being cured into a thermoset plastic with the fibers. Processes for preparing a binder composition for organic or inorganic fibers are also described. The processes may include providing an aqueous solution of polycarboxylic acid polymers, where the polymers comprise about 10%, by wt., to 100%, by wt., of a butenedioic acid or butenedioic anhydride; adding a polyol to the aqueous solution; and maintaining the pH of the aqueous solution at about 5 or more.

FIELD OF THE INVENTION

Binding compositions are described for use with fibers. Morespecifically, the subject invention pertains to a curable bindercompositions that can be prepared at a pH greater than 4. The bindercompositions can replace formaldehyde-based binders in fiber containingproducts.

BACKGROUND OF THE INVENTION

Binder compositions for fiber containing products have a variety of usesthat include stiffening applications where the binder is used to stiffena fiber containing product; thermo-forming applications wherein thebinder resin is applied to a sheet or lofty fibrous product, followingwhich it is dried and optionally B-staged to form an intermediate andstill curable product; and forming fully cured systems such as buildinginsulation.

One important application of binder compositions is to form fibrousglass into insulation. Fiberglass insulation generally includes mattedglass fibers bonded together by a cured thermoset polymeric material.Molten streams of glass are drawn into fibers of random lengths andblown into a forming chamber where they are randomly deposited as a matonto a traveling conveyor. The glass fibers, while in transit in theforming chamber and still hot from the drawing operation, are sprayedwith an aqueous binder composition. The residual heat from the glassfibers and the flow of air through the fibrous mat during the formingoperation are generally sufficient to volatilize water from the binder,thereby leaving the remaining components of the binder on the fibers asa viscous or semi-viscous high solids liquid. The coated fibrous mat istransferred to a curing oven where heated air is blown through the matto cure the binder and rigidly bond the glass fibers.

Conventional binder compositions for fiberglass includephenol-formaldehyde binders, which are favored for their low cost andthe ability to go from a low viscosity liquid in the uncured state to arigid thermoset polymer when cured. A low viscosity uncured binderallows the mats to be properly sized. In contrast, viscous binders areusually sticky and promote fiber accumulation on surfaces of theproduction equipment. Some of this accumulated fiber inevitably falls onthe mat, causing dense areas and defects in the fiberglass. After thebinder composition is applied and cured, however, it should betransformed from a low viscosity liquid to a rigid matrix. This allowsthe fiberglass insulation to spring from a compressed volume whenpackaged, back to its uncompressed full size when installed.

Numerous thermosetting polymers can go from low viscosity liquids torigid polymer matrices when cured. However, binder-coated fiberglass istypically viewed as a commodity, and subject to intense cost pressures.The economics rule out the use of most thermosetting polymer resins,including many polyurethanes and epoxies, among other resins. Thesuccess of phenol-formaldehyde resins is due in part to their excellentcost/performance ratio. Phenol-formaldehyde resins can be economicallyproduced, and can be extended with urea prior to use as a binder in manyapplications. Such urea-extended phenol-formaldehyde binders have beenthe mainstay of the fiberglass insulation industry for years.

More recently, concerns about emissions of volatile organic compound(VOCs) and other environmental contaminants have provided an impetus toreduce the use of formaldehyde-based binders. Fiberglass producers haveexperimented with changes in the ratio of phenol to formaldehyde in thephenol-formaldehyde resole resins, as well as changes in catalysts, andthe addition of formaldehyde scavengers. While these changes haveresulted in considerable improvement in emissions from the binders,increasingly stringent government regulations have encouraged producersto formulate binders that are essentially formaldehyde free.

One alternative binder formulation replaces the phenol-formaldehyde withpolycarboxy polymers. While the polycarboxy binders are cost competitivewith phenol-formaldehyde from a materials standpoint, they can be toughon manufacturing equipment. The polycarboxy binders are made under veryacidic conditions, typically starting with aqueous solutions of acrylateand/or methacrylate monomers (e.g., acrylic acid and/or methacrylicacid) that have a pH of about 2 to 4. Production equipment that comes incontact with these solutions often requires repair and replacement at anaccelerated pace due to the highly acidic environment. Thus, there is aneed for binder compositions and method of making them that does notrequire such highly acidic conditions. These and other problems areaddressed here.

BRIEF SUMMARY OF THE INVENTION

Binder compositions and methods of making them are described where thepH of the pre-cured binder solution and the cured binder product have apH higher than conventional polycarboxy binder formulations. The presentbinder solutions may be made and cured at pHs of about 4.5 or more(e.g., about 4.5 to about 9). These higher pHs may also extend to thecured binder and fiber products, which may have a pH of about 4.5 ormore, 5 or more, etc.

These higher pH binder compositions are more tolerated by processingequipment that comes in contact with the binder solutions. It alsoallows the binders to be used with equipment made from less acidresistant materials, which can reduce equipment costs. The higher pH ofthe cured products (e.g., fiberglass mat) is also more compatible withacid sensitive building materials like metal beams and fasteners.

Embodiments of the invention include compositions for binding organic orinorganic fibers. The compositions may include an aqueous solutionhaving a pH of about 4.5 or more. The aqueous solution may include apolycarboxy polymer that is about 10%, by wt., to 100%, by wt., of abutenedioic acid or butenedioic anhydride; a polyol; and optionally across-linking catalyst. The compositions can maintain a pH of about 5 ormore after being cured into a thermoset plastic with the fibers.

Embodiments of the invention also include processes for preparing abinder composition for organic or inorganic fibers. The processes mayinclude the step of providing an aqueous solution of polycarboxylic acidpolymers, where the polymers comprise about 10%, by wt., to 100%, bywt., of a butenedioic acid or butenedioic anhydride. The processes mayalso include the steps of adding a polyol, and optionally across-linking catalyst, to the aqueous solution; and maintaining the pHof the aqueous solution at about 5 or more.

Embodiments of the invention may still also include processes forbinding organic or inorganic fibers. The processes may include the stepof applying a binder composition on the fibers. The binder compositionmay have a pH of about 4.5 or more, and may include a polycarboxypolymer that is about 10%, by. wt., to 100%, by wt., of a butenedioicacid, a polyol, and optionally a cross-linking catalyst. The processesmay also include the step of curing the binder composition to form anarticle comprising a thermoset plastic and the fibers.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the invention. The features and advantages ofthe invention may be realized and attained by means of theinstrumentalities, combinations, and methods described in thespecification.

DETAILED DESCRIPTION OF THE INVENTION

Polycarboxy binder compositions are described that can efficiently forma cross-linked binder polymers at pHs of about 4.5 or more. The bindercompositions include a polycarboxylic acid that may be made partially orexclusive from a butenedioic acid or butenedioic anhydride. Thecompositions also include a crosslinking compounds that react with thepolycarboxylic acid (with or without the presence of a cross-linkingcatalyst) at a curing temperature and pH of about 4.5 or more, to form arigid thermoset polymer.

The polycarboxy binders in the uncured state have low viscosity makingthem easy to apply to fibers. When the mixture of binder composition andfibers are cured, a fiber reinforced polymer is formed. These fiberreinforced binders have a variety of applications, including fiberglassinsulation.

The binder polymers may include polycarboxylic acids that in the curedstate are crosslinked with one or more crosslinking compound. Thepolycarboxylic acids may be synthesized via a reaction of ethylenicallyunsaturated monomers that contain carboxylic acids and/or acidanhydrides. They may also be formed from the condensation of monomerscontaining multifunctional carboxylic acids and/or acid anhydrides thatleave unreacted carboxylic acid moieties. When monomer or polymer unitscontain multiple anhydride moieties, they may be converted topolycarboxylic acid moieties by hydrolysis with water.

Examples of carboxylic acids that may be used to make the polycarboxyacids may include saturated or unsaturated organic acids that may haveone or more carboxylic acid moieties. Specific examples include acrylicacid, methacrylic acid, a butenedioic acid (i.e., maleic acid and/orfumaric acid), among other carboxylic acids. Examples of acid anhydridesthat may be used to make the polycarboxylic acids include saturated orunsaturated anhydrides that have one or more anhydride moieties.Specific examples include acrylic anhydrides, methacrylic anhydrides,itaconic anhydrides, and butenedioic anhydrides (e.g., maleicanhydride), among other anhydrides.

The polycarboxylic acids may also include copolymers of carboxylic acidsand/or anhydrides, and ethylenically unsaturated monomers that do notcontain a carboxylic acid or anhydride moiety. Examples of theseco-monomer groups include ethylene, propylene, styrene, butadiene,acrylamide, acrylonitrile, and (meth)acrylate esters, among othergroups.

The polycarboxylic acids may contain from about 10% to about 100%, bywt., butenedioic acid and/or butenedioic anhydride. When thepolycarboxylic acid is made from less than 100% butenedioic acid and/orbutenedioic anhydride, other carboxylic acids, carboxylic anhydrides,and/or ethylenically unsaturated monomers may make up the rest of thepolycarboxylic acid.

When the polycarboxylic acid contains free carboxylic anhydridemoieties, a hydrolysis step may be performed to convert the anhydridesinto carboxylic acid moieties. In some embodiments, a catalyst may beadded to facilitate the hydrolysis. For example and alkaline catalystsuch as alkali metal hydroxides, alkali earth metal hydroxides, tertiaryamines, ammonium hydroxide, among other alkaline compounds may be addedto the aqueous solution to help catalyze the hydrolysis. For example,styrene-maleic anhydride (SMA) may undergo a alkaline catalyzedhydrolysis in water to form a styrene-maleic acid polycarboxylic acid.

The binder compositions may also include one or more crosslinkingcompounds that react with the polycarboxylic acids to form crosslinkedpolymers. Typically, these compounds contain one or more moieties thatreact with carboxylic acid functional groups of mono- or polycarboxycompounds to form a covalent bonds. Classes of these crosslinkingcompounds may include polyols (i.e., alcohols with a plurality ofhydroxyl groups) such as polyester polyols, polyether polyols, acrylicpolyols, glycols, alkanol amines, amines, diamines, polyamines, epoxies,carbodiimides, aziridines, and other types of compounds with functionalgroups that promote crosslinking of the binder polymers. Specificglycols may include ethylene glycol, propylene glycol, glycerol,diethylene glycol, and triethylene glycol, among other glycols. Specificalkanol amines may include ethanol amine, diethanol amine, andtriethanol amine, among other alkanol amines. Specific polyamines mayinclude ethylene diamine, hexane diamine, and triethylene diamine, amongother polyamines. Specific epoxies may include bisphenol-A basedepoxies, aliphatic epoxies, and epoxidized oils, among other epoxycompounds.

The present binder compositions may be applied to a variety of fibers.These fibers may include organic and/or inorganic fibers. Organic fibersmay include fibers made from organic polymers such as polyamide fibers,polypropylene fibers, polyester fibers, and/or polyaramide fibers, amongother organic polymer fibers. Inorganic fibers may include glass fibers(e.g., silicon oxide), ceramic fibers (e.g., silicon carbide), basalt,inorganic carbon, metals, and metal oxides, among other materials. Thefibers may be arranged as a woven mat or textile, or a non-woven mat orbulk.

The binder compositions may be applied as a flowable liquid to thefibers. Typically the compositions are aqueous solutions, butembodiments may also include organic solutions where the binder polymerare dissolved in an organic solvent, emulsions of the binder in water,and neat liquids of undissolved binder polymers.

In addition to the binder polymers, the binder compositions may alsooptionally include one or more cross-linking catalysts (sometimes calledaccelerators) that promote the polymerization of polycarboxylic acidsand crosslinking compounds like the polyols. Cross-linking catalysts mayinclude phosphorous-containing compounds such as phosphorous oxyacidsand their salts. For example, the cross-linking catalyst may be analkali metal hypophosphite salt like sodium hypophosphite (SHP).

The binder compositions may also optionally include an initiator such asbenzophenone, azoisobutyronitrile, cumyl hydroperoxide, benzoylperoxide, and/or catalysts such as triethyl amine, and cobalt octanoate.These compounds may be added to expedite curing of the bindercomposition on glass fibers.

The binder compositions may also include an organic or inorganicextender. Specific examples of extenders include starch, lignin, rosin,polymers, and clays, among other extenders.

In addition the binder compositions may include adhesion promoters,oxygen scavengers, solvents, emulsifiers, pigments, fillers,anti-migration aids, coalescents, wetting agents, biocides,plasticizers, organosilanes, anti-foaming agents, colorants, waxes,suspending agents, anti-oxidants, secondary crosslinkers, as well ascombinations of these types of compounds.

As noted above, the binder compositions may be coated on a variety offibers. Specific applications include coating the compositions on glassfibers to make fiberglass insulation. When the fiberglass is amicroglass-based substrate, the binder may be applied and cured to formprinted circuit boards, battery separators, filter stock, andreinforcement scrim, among other articles.

The binder compositions can be coated on fibers using a variety oftechniques. For example, the binder compositions may be spray coated,spin-curtain coated, or dipping-roll coated, among other techniques. Thecomposition may be applied to freshly-formed fiberglass, or tofiberglass following collection.

After application of the low-viscosity fiber composition on the fibers,the amalgam may undergo curing, wherein the binder polymers undergofurther chemical reaction to form a thermoset plastic coating. In someembodiments curing is conducted at ambient temperature, and in otherembodiments the curing is conducted at elevated temperature (e.g., up to300° C.) to expedite the formation of a stable and secure polymercoating. The peak curing temperature may depend in part on the componentof the binder composition, such as whether a curing catalyst is present.

The cured binder at the conclusion of the curing step is typicallypresent as a secure thermoset polymer coating that may represent about0.5% to about 50%, by wt. (e.g., about 1% to about 10%, by wt.) of thefiber reinforced article.

The polycarboxy binder compositions provide a formaldehyde-free way tomake formaldehyde-free fiber reinforced products. They also provideadvantageous flow properties, and offer the possibility of lower binderusage, lower overall energy consumption, decreased water usage, and lesswear on production equipment. These improvements and others result inmore cost effective ways of producing fiber reinforced products.

EXPERIMENTAL Experiment #1

An aqueous solution of Styrene-Maleic Anhydride (SMA) was hydrolyzed toform Styrene-Maleic Acid. In a flask equipped with a reflux condenser,6.68 g of sodium hydroxide (NaOH) was added to 250 g of water. To thissolution, 160 g of SMA was added and stirred until partially dissolved.The solution was heated to 90° C. for several hours to produce a clearsolution of SMAcid at 40% solid level. The molar ratio of SMA:NaOH was4:1 resulting in a polymer with an acid:salt ratio of 7:1. The acidequivalent of the resin was 142.9 g/mol.

To 35.75 g or the resin solution was added 5.0 g of triethanol amine(TEA). In some test runs 0.39 g of sodium hypophosphite (SHP) as anaccelerator at 2%, by wt, while in other test runs no accelerator wasadded to the formulation. The mixture was stirred until uniform. TheAcid:OH ratio of the resulting resin was 1:1. DMA indicated the resincured at below 200° C. to form a rigid polymer. The viscosity of the41.7% solid solution was 3,600 cps an the pH of the resin was 4.5, bothbefore and after the addition of the SHP. The resin cured on fiberglassat 6-25% resin level at 200° C. for those formulations without SHP, and180° C. for formulations that included the SHP accelerator. All sampleswere white, rigid and highly water resistant.

Experiment #2

The experimental setup of Example #1 was repeated except forsubstituting 6.66 g of diethanol amine (DEA) for the TEA. Following thecure of the binder composition, the resin produced a white, rigid andhighly water resistant bat.

Experiment #3

The experimental setup of Example #1 was repeated except the amount ofTEA used was increased to 8.33 g. Following the cure of the bindercomposition, the resin produced a white, rigid and highly waterresistant bat.

Experiment #4

The experimental setup of Example #1 was repeated except the amount ofTEA used was increased to 10 g. Following the cure of the bindercomposition, the resin produced a white, rigid and highly waterresistant bat.

Experiment #5

The experimental setup of Example #1 was repeated except forsubstituting 7.0 g of Michael adducts of DEA/acrylic acid (2:1 mol:mol)for the TEA. Following the cure of the binder composition, the resinproduced a white, rigid and highly water resistant bat.

Experiments #6-8 used an ammonium hydroxide (NH₄OH) solution to reducethe viscosity of the resin.

Experiment #6

The experimental setup of Example #1 was repeated except for adding 1%,by wt., of a 28% solution of NH₄OH. Viscosity of the 41.7% solidsolution was reduced to 1,440 cps and the pH of the resin increased to5.5 both before and after the addition of the SHP. Following the cure ofthe binder composition, the resin produced a white, rigid and highlywater resistant bat.

Experiment #7

The experimental setup of Example #1 was repeated except for adding 2%,by wt., of a 28% solution of NH₄OH. Viscosity of the 41.7% solidsolution was reduced to 511 cps and the pH of the resin increased to6.5, both before and after the addition of the SHP. Following the cureof the binder composition, the resin produced a white, rigid and highlywater resistant bat.

Experiment #8

The experimental setup of Example #1 was repeated except for adding 3%,by wt., of a 28% solution of NH₄OH. Viscosity of the 41.7% solidsolution was reduced to 286 cps and the pH of the resin increased to7.5, both before and after the addition of the SHP. Following the cureof the binder composition, the resin produced a white, rigid and highlywater resistant bat.

Experiment #9

5.0 g of TEA is dissolved in 16.8 g or water. Then 11.8 g of poly-maleicacid is added and stirred at ambient temperature until it is fullydissolved. Under cure conditions (including with and without SHPaddition) of Example #1, the resin produced is a white and rigid waterresistant bat.

Corrosion Resistance Measurements:

Resin solutions of Examples #1, 6, 7, and 8 were evaluated for theirability to corrode steel. The corrosion tests included providingstandard pre-weighted steel corrosion coupons in a 10% aqueous bindersolution. The binder was stirred for 24 hours at 25° C. Then the couponswere rinsed with deionized water, dried, and weighed. The levels of ironleached into the resin from the steel coupons was also measured. Thetest results showed that four resins made according to Examples #1, 6,7, and 8 had lower corrosion rates than a conventional resin made frompolyacrylic acid and TEA.

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theinvention. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent invention. Accordingly, the above description should not betaken as limiting the scope of the invention.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassed.The upper and lower limits of these smaller ranges may independently beincluded or excluded in the range, and each range where either, neitheror both limits are included in the smaller ranges is also encompassedwithin the invention, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a process” includes aplurality of such processes and reference to “the catalyst” includesreference to one or more catalysts and equivalents thereof known tothose skilled in the art, and so forth.

Also, the words “comprise,” “comprising,” “include,” “including,” and“includes” when used in this specification and in the following claimsare intended to specify the presence of stated features, integers,components, or steps, but they do not preclude the presence or additionof one or more other features, integers, components, steps, acts, orgroups.

1. A composition for binding organic or inorganic fibers, thecomposition comprising: an aqueous solution having a pH of about 4.5 ormore, wherein the aqueous solution comprises: a polycarboxy polymer thatis about 10%, by wt., to 100%, by wt., of a butenedioic acid orbutenedioic anhydride, and a polyol, wherein the composition maintains apH of about 5 or more after being cured into a thermoset plastic withthe fibers.
 2. The composition of claim 1, wherein the compositionfurther comprises a cross-linking catalyst.
 3. The composition of claim1, wherein the butenedioic acid comprises maleic acid or fumaric acid,and the butenedioic anhydride comprises maleic anhydride.
 4. Thecomposition of claim 1, wherein the polycarboxy polymer is a co-polymerof maleic acid or maleic anhydride and a second unit selected from thegroup consisting of acrylic acid, acrylic anhydride, methacrylic acid,methacrylic anhydride, ethylene, propylene, acrylamide, acrylonitrile,(meth)acrylate, fumaric acid, and styrene.
 5. The composition of claim1, wherein the polycarboxy polymer comprises styrene-maleic acid.
 6. Thecomposition of claim 5, wherein the maleic acid is about 10%, by mol.,to about 100% by of the polycarboxy polymer.
 7. The composition of claim1, wherein the polyol is selected from the group consisting of ethyleneglycol, propylene glycol, a polyether polyol, di-ethylene glycol,triethylene glycol, ethanol amine, diethanol amine, triethanol amine, apolyester polyol, a polyether polyol, an acrylic polyol, ethylenediamine, hexane diamine, triethylene diamine, a bispheno-A epoxy, aaliphatic epoxy, and an epoxidized oil.
 8. The composition of claim 2,wherein the cross-linking catalyst comprises a phosphorous oxyacid salt.9. The composition of claim 8, wherein the cross-linking catalyst issodium hypophosphite.
 10. The composition of claim 1, wherein theaqueous solution has a pH between about 4.5 and about
 9. 11. Thecomposition of claim 1, wherein the aqueous solution further comprisesan alkaline compound selected from the group consisting of alkali metalhydroxides, alkali earth metal hydroxides, and tertiary amines.
 12. Thecomposition of claim 1, wherein the aqueous solution further comprisessodium hydroxide.
 13. A process for preparing a binder composition fororganic or inorganic fibers, the process comprising: providing anaqueous solution of polycarboxylic acid polymers, wherein the polymerscomprise about 10%, by wt., to 100%, by wt., of a butenedioic acid orbutenedioic anhydride; adding a polyol to the aqueous solution; andmaintaining the pH of the aqueous solution at about 5 or more.
 14. Theprocess of claim 13, wherein the process further comprises adding across-linking catalyst to the aqueous solution.
 15. The process of claim13, wherein the butenedioic acid comprises maleic acid or fumaric acid,and the butenedioic anhydride comprises maleic anhydride.
 16. Theprocess of claim 13, wherein the polycarboxylic acid polymers arecopolymers of maleic acid or maleic anhydride and a second unit selectedfrom the group consisting of acrylic acid, acrylic anhydride,methacrylic acid, methacrylic anhydride, ethylene, propylene,acrylamide, acrylonitrile, (meth)acrylate, fumaric acid, and styrene.17. The process of claim 13, wherein the polyol is selected from thegroup consisting of ethylene glycol, propylene glycol, a polyetherdi-ethylene glycol, triethylene glycol, ethanol amine, diethanolamine,triethanol amine, a polyester polyol, a polyether polyol, an acrylicpolyol, ethylene diamine, hexane diamine, triethylene diamine, anaromatic epoxy, an aliphatic epoxy, and an epoxidized oil.
 18. Theprocess of claim 14, wherein the cross-linking catalyst comprises sodiumhypophosphite.
 19. The process of claim 13, wherein the pH of theaqueous solution maintained in a range from about 4.5 to about
 9. 20.The process of claim 13, wherein maintaining the pH of the aqueoussolution comprises adding a hydroxide base to the solution.
 21. Theprocess of claim 20, wherein the hydroxide base is sodium hydroxide. 22.The process of claim 13, wherein the process further comprises addingammonium hydroxide to the aqueous solution. 23-34. (canceled)